When I open my previously saved and working project, I get a Debug Event with a keyframe h-142 message (see below).

The workaround proposed in adobe help under Keyframe.h-142 error | Opening projects does not work. I guess because PE13's .prel files are not in plain text format as PE12 and previously, therefore the workaround with perl will not deliver the required results.

1) rename my corrupt.prel file to corrupt.zip (when opening the file in notepad++, I saw a lot of gibberish and thought the file might be zipped, which it is. I am not sure whether this is only the case in PE13).